122 CHAPTER 6 LIGHT-VESSELS - LIGHT TOWERS and LANBYS 6.1 GENERAL Light-vessels are heavily-anchored vessels fitted with a light of high intensity. They are specially built to serve as beacons (Figure 6.1). Allthough light-vessels are scarcely encountered anymore, we still find it useful to describe them in some detail. They have in fact been replaced by light towers and/or floating structures (Lanby Buoys). Light-vessels serve the same purpose as lighthouses and are used only when it is impracticable to construct a lighthouse at the desired site. They are mainly anchored where sea traffic is heavy and navigation is potentially dangerous. They are also used to mark the channels or fairways at the entrances to estuaries and harbours. Light-vessels may be relied upon to the same degree as lighthouses, as they are constantly manned which is not, of course, the case with buoys. By day, light-vessels are identified by their colour. Their lights are positioned at a considerable height above the midships and their high masts carry the radiobeacon aerials. Most light-vessels are painted red and bear the name of the station in large white letters on both sides of the hull. Dutch light-vessels have a large white band with black letters. Light-vessels usually bear the name of the bank they mark. Some light-vessels, such as those of Belgium carry in the foremast a daymark in the shape of a truncated cone of the same colour as the vessel. English light-vessels no longer carry this mark.
Figure 6.1 - Former South Goodwin Light-Vessel
123 In compliance with the International Regulations for Preventing Collisions at Sea, 1972, light-vessels shall by day exhibit a black ball; at night, they shall exhibit an all-round white light, where it can best be seen. This light is, however, mostly carried on the forestay as, in that position, it indicates how the light-vessel is riding with regard to the current. Some light-vessels exhibit two anchor lights; one in the fore part not less than 6 metres above the hull and one at the stern, at least 4.50 metres lower than the forward light. (See International Regulations 1972, Rule 30.) The single anchor light carried at the forestay is often called ‘riding light’. The observations made in Chapter 5 about the lights of landmarks are also applicable to light-vessels. If for any reason, English light-vessels cannot exhibit their usual characteristic light whilst at their station, the anchor light only will be shown. Other light-vessels shall exhibit the reserve lights which are given in the column ‘Remarks’ in the lists of lights. When light-vessels, whether English, Dutch, French, or Belgian, are off their station or adrift so that they are no longer of use as a guide to navigation, they adopt the following procedures : The usual characteristic light is no longer shown and the fog and radio beacon signals are discontinued. Daymarks are struck so far as is practicable. AT NIGHT: they exhibit two red lights, one foreward and one aft, and simultaneously at intervals of not more than 15 minutes, one red and one white flare. Instead of these flares they may exhibit a red and a white light every minute. BY DAY: they exhibit two black balls, one foreward and one aft and in addition, the group LO of the International Code Signals, where it can best be seen. (LO = I am not in my correct position). Light-vessels of some nations, when adrift, may be required to carry other lights or marks. The introductiory notes in each list of lights should be consulted for the appropriate information. In fog or restricted visibility, light-vessels also exhibit their light by day, but when out of position, the light is extinguished and they shall sound signal prescribed for vessels at anchor. When underway, on passage to their station or harbour they show the lights and make the same sound signals as other vessels of their length. (See International Regulations 1972.) By day if they are proceeding under their own power, they exhibit two black balls, one foreward and one aft. Most light-vessels are equipped with radio telephones. This equipment is used only in cases of distress or when urgent assistance is needed; it is thus not used for normal listening. Some light-vessels may receive or address messages to passing vessels by using the International Code Flags or the morse lamp.
124 6.2 WATCH BUOYS One or two ‘watch buoys’, also called ‘station buoys’, are usually moored off light-vessels. In the new Maritime Buoyage System (IALA “A”), watch buoys are included in the category ; ‘Special marks’ and are therefore painted yellow (Figure 6.2). In the former Uniform Buoyage System (Geneva 1936) they were generally painted red, unlighted, and can or cone shaped. English watch buoys carry the name of the light-vessel followed by the word ‘watch’. Watch buoys moored off Belgian light-vessels carry only the abbreviation of the light-vessel’s name. Some watch buoys bear a white reflective tape called ‘scotchlite’ with the light-vessel’s name in black letters. They commonly also carry a topmark in scotchlite. Watch buoys make it possible to ascertain by means of bearings whether the light-vessel is in position. This is especially important after a gale.
Figure 6.2 - Light-vessel with watch buoy 6.3 INDICATION IN THE LISTS OF LIGHTS In all lists of lights the names of light-vessels are printed in italic capitals. Data, similar to that of ordinary lights is given first, followed, in the column `Remarks’ by additional information concerning : —— the anchor light (riding light); —— the operation of the day light in restricted visibility; —— reserve lights when the main light is out of use; —— the fog signal and reserve fog signal; —— storm signals;
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—— the geographical position of the light-vessel; —— the ability of the light-vessel to address messages by International Code Flags, or by morse lamp; —— the positions of the watch buoys, their shapes, colours, names and topmarks, and radar reflectors, etc. if fitted. 6.4 INDICATION ON CHARTS A small symbol is used to depict a light-vessel on charts. The position is given by a small circle in the centre of the base of the symbol. The light is shown by a magenta light flare. A magenta circle means that the light-vessel is equipped with a radiobeacon. Following the symbol information is given about the colour, elevation, and range of the light, and the characteristics of the fog signal. Watch buoys placed near a light-vessel are also shown on charts (Figure 6.3).
Figure 6.3 — Former West Hinder Light-vessel with its watch buoys Extract from the old English chart No. 323 Dover strait - Eastern Part
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RISK OF COLLISION WITH LIGHT-VESSELS There are several recorded instances of ships having collided with light-vessels. Such accidents may not only result in loss of life but also in damage to or loss of an important aid to navigation. In order to avoid such catastrophies, mariners should take the following precautions when approaching a light-vessel : a. b. c. d.
pass any light-vessel at a safe distance; never pass ahead of a light-vessel; never pass between the light-vessel and one of her watch buoys; make due allowance for drift due-to tide and wind. The direction in which the light‑vessel is riding is a valuable indicator to the direction in which the current is setting; e. avoid rounding a light-vessel by taking successive constant bearings, especially when bearings from her radiobeacon are used; f. alter course in ample time to avoid risk of collision when making a straight course for a light-vessel and particularly in restricted visibility; g. make due allowance for the likely reduced power of the light and fog signal in the case of temporary replacement of the light-vessel by a relief light-vessel. In these circumstances the distance can be over estimated due to the reduced power of the light and/or fog signal. In case of collision with a light-vessel, it is the duty of the master to give immediate assistance and to take all necessary measures to inform the appropriate authorities. 6.6 WITHDRAWAL OF A LIGHT-VESSEL It may be necessary, after a collision for instance, to withdraw a light-vessel for repairs. This may be done without notice. The withdrawn light-vessel is not necessarily replaced by a relief vessel. In some cases, the damaged vessel may be replaced by another light-vessel with different characteristics. Relief light-vessels are usually painted in the same colour as the regular light-vessel and may carry the words ‘Relief’ or ‘Reserve’ on both sides. 6.7 REPLACEMENT OF LIGHT-VESSELS Light-vessels are very costly to maintain. Consequently, for many years, Trinity House has been seeking to develop more economical light systems. There are two possibilities : 1. fi xed structures in places where it is possible to construct them, for instance,
127 ‘light towers’ (Figure 6.4 and 6.5); 2. large automatic navigational buoys in places where it is impracticable or impossible to construct light towers and where floating buoyage is imperative. These ‘light-floats’ are called ‘Lanby Buoys’ or simply ‘Lanbys’ (Figures 6.6, 6.7, and 6.8). Trinity House is the official British authority, having the power to erect and maintain lights for navigational purposes. It is responsible for landmarks and buoys; also for visual, audible and electronic aids to navigation in England, Wales, the Channel Islands and Gibraltar. Trinity House is also responsible for pilotage in the United Kingdom, specifically for London and forty other districts. (There is a separate Scottish authority.) In America, the erection and maintenance of aids to navigation is carried out by the United States Coast Guard. American aids to navigation number well over 46.000. 6.7.1 Light towers Although the construction cost of fixed light towers at sea is high compared with that of light-vessels, Trinity House expects to make considerable savings on maintenance and manning. These structures will be highly automated and will only require small crews. They will normally be provided with a small helicopter landing surface. Kirsh Tower, Royal Sovereign, Inner Dowsing and Goeree are or were) a few stations already in use. The Royal Sovereign (Figure 6.4) was the first light tower to replace a light-vessel. Fixed structures which have the appearance of lighthouses are very often seen along coasts and on large rivers. They are also called ‘beacon towers’ (Figure 6.5).
Figure 6.4 Figure 6.5 Royal Sovereign Light Tower Fixed structure in a channel
Courtesy U.S. Coast Guard
128 6.7.2 Floating structures’ (Lanby Buoys) Where fixed structures cannot be constructed, light-vessels are replaced by ‘lanby buoys’ (large automatic navigation buoys). These are large discus-shaped buoys with a high superstructure. Lanby buoys commonly have a displacement of about 80 tons, (40 tons of material and 40 tons of sea water ballast) and a diameter of about 12 metres (40 feet) (Figures 6.6 to 6.9). They carry a much more powerful light and fog signal than any other buoy and their operation is fully automatic. The light is also much higher and may be sited up to 12 metres above sea level. Power is supplied by diesel generators and, in case of failure, these can automatically be switched over to reserve equipment. They have several electronic aids including ‘racon’ and radiobeacons. The machinery can work without maintenance for six months or more. Figure 6.7 shows a diagram of the American lighthouse buoy Mk II LNB. Indication on charts Floating structures such as lanbys are indicated on charts by the following symbols :
ordinary lanby mark;
tanker mooring of superbuoy size;
ODAS data-collecting buoy (Ocean Data-Acquisition System) of superbuoy size.
NOTES 1. Floating structures or Lanby Buoys are also called lighthouse buoys. 2. In America the term Large Navigational Buoys - L.N.B’s is used. 6.7.3 Oceanographic and weather buoys At sea, and sometimes very far from the coast, mariners may encounter very large buoys, which are specially intended to record and transmit oceanographic and meteorological data (weather data buoys). Their main purpose is to replace the oceanographic and weather ships which have become too expensive to run. Every hour a computer system housed inside the buoy stores data from certain observations such as : air and seawater temperature, atmospheric pressure, direction and force of wind, dewpoint, solar radiation, precipitation, surface water currents etc. Every six hours this data is transmitted ashore by radio link.
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Figure 6.6 Courtesy U.S. Coast Guard
Figure 6.7 - Lanby
Figure 6.8 - Lanby
Courtesy U.S. Coast Guard
The oceanographic and weather buoy shown in Figure 6.10 weighs 100 tons, has a diameter of 12 metres, and a pylon about 14 metres high which carries the arial and the meteorological instruments. This experimental buoy known as the ‘X-ERB-1 weather buoy’ is anchored 125 miles east of Norfolk Virginia and has a two-man crew. It keeps storm watch for the Atlantic Coast.
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Figure 6.9
Figure 6.19
Oceanographic and Weather
IMPORTANT REMARK Some information in this Chapter may be obsolete at the present time. Please check any up to date Sailing Instruction (List of Lights, Pilot Books, Notices to Mariners, Charts, etc.) for more recent information.
